In certain types of chemical processes, it is necessary to feed finely-divided solid materials to a liquid medium. Considerable difficulties are encountered in introducing finely-divided solids into such reaction systems, particularly where the reaction system must be sealed from the atmosphere.
An example of a system in which a solid material must be added to a liquid reaction system sealed from the atmosphere is the introduction of finely-divided solid catalysts into olefin polymerizations that are carried out in a liquid hydrocarbon medium. A common method for introducing such catalyst solids to the liquid polymerization medium is to suspend the catalyst solids in a hydrocarbon medium, feed such a suspension to a cup maintained in a rotatable valve, and then to rotate the valve to dump the catalyst solids into the reaction medium. A typical catalyst feeding system of this type is shown in U.S. Pat. No. 3,257,363. By feeding the catalyst solids to the reaction medium in this manner, the catalyst is added to the reaction medium in finite charges on a discontinuous basis. As a consequence, in most instances, the concentration of catalyst particles varies in different sections of the polymerization medium. In view of the problems of obtaining uniform dispersions of such finely-divided solids in a reaction medium, it would be desirable to have available to the art methods for feeding such finely-divided solids to a reaction system on a truly continuous and uniform basis.